It is known to construct motor vehicle doors from an inner panel and an outer panel which are spaced apart to define a cavity in which window regulators, door latches and other mechanisms are mounted. Such doors typically have a window frame which surrounds a window opening.
Prior patents have disclosed door constructions in which either or both of the panels were constructed of molded synthetic resin plastic parts.
One shortcoming of the use of plastics in the construction of vehicle doors is that the plastic material has somewhat limited strength which necessitates the use of metal or glass fiber reinforcements.
Another shortcoming of the use of plastic in vehicle doors is that plastic materials which have reinforcements therein tend to provide a poor surface finish for subsequent painting, while materials which have high surface quality for subsequent painting may have insufficient strength for the structural requirements of the vehicle door.
The present invention provides a new and improved method of making a vehicle door uniquely constructed and configured to provide both high strength and good surface finish for subsequent painting.
According to the invention, a vehicle door includes an outer panel and an inner panel of molded synthetic resin construction can be manufactured. The inner panel has a structural lower portion concealed beneath the outer panel and an upper portion integral with the lower portion and defining a window frame surrounding a window opening. A tubular reinforcement member of generally inverted U shape is embedded in the upper portion of the inner panel and has leg portions extending downwardly from the upper portion and embedded in the structural lower portion so that the structural lower portion connects the leg portions of the upper portion. The tubular member is a continuous hollow tube formed to have varying cross sectional shape along the continuous length to fit within the shape of the window frame. The synthetic resin of the upper portion is a reinforced reaction injection molded (RRIM) material providing a finished surface for painting and the synthetic resin of the lower portion is a structural reaction injection molded (SRIM) material providing relatively high strength and having a glass fiber mat embedded therein to span between the legs of the tubular member and facilitate bonding between the resin materials of the upper and lower portions.
A copending application, Ser. No. 07/445,248 filed Dec. 4, 1989 now U.S. Pat. No. 4,945,602 by the present inventors assigned to the common assignee disclosed and claimed the novel structure of a motor vehicle door.
Accordingly, the object, feature, and advantage of the invention resides in the provision of a new and improved plastic vehicle door including an inner panel having a tubular reinforcement member of inverted U-shape embedded in the upper portion to define a window opening and having leg portions extending downwardly and embedded in a structural lower portion.
Another feature, object, and advantage of the invention resides in the provision of a tubular member embedded in the window frame forming portion of a molded plastic door panel and having varying cross sectional shape along the length thereof to fit within the cross section of the window frame.
A still further feature, object, and advantage of the invention resides in the provision of an inner panel for a vehicle door having an integrally molded upper portion defining a window opening and providing a finished surface for painting and having a lower portion of structural molded material with a glass fiber mat embedded therein.
A still further feature, object, and advantage of the invention resides in the provision of a vehicle door panel comprised of upper and lower portions with a tubular metal reinforcement embedded in the upper portion and glass fiber mat embedded in the lower portion and spanning between the upper and lower portions and extending between the spaced apart legs of the tubular reinforcement member.
A still further feature, object and advantage of the invention resides in the provision of a two-staged or sequential reaction injection molding (RIM) method of manufacturing a glass fiber mat reinforced plastic part having at least one appearance surface in which a high viscosity RIM material and a low viscosity RIM material are sequentially injected into a mold cavity containing at least one reinforcing member of a glass fiber mat.